crypto encryption and decryption/codes/monoalphabatic.java
<gh_stars>0class GFG {
	public static char normalChar[]
		= { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
			'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r',
			's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
	public static char codedChar[]
		= { 'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O',
			'P', 'A', 'S', 'D', 'F', 'G', 'H', 'J', 'K',
			'L', 'Z', 'X', 'C', 'V', 'B', 'N', 'M' };
	// Function which returns encrypted string
	public static String stringEncryption(String s)
	{
		// initializing an empty String
		String encryptedString = "";
		// comparing each character of the string and
		// encoding each character using the indices
		for (int i = 0; i < s.length(); i++) {
			for (int j = 0; j < 26; j++) {

				// comparing the character and
				// adding the corresponding char
				// to the encryptedString
				if (s.charAt(i) == normalChar[j])
				{
					encryptedString += codedChar[j];
					break;
				}
				// if there are any special characters
				// add them directly to the string
				if (s.charAt(i) < 'a' || s.charAt(i) > 'z')
				{
					encryptedString += s.charAt(i);
					break;
				}
			}
		}
		// return encryptedString
		return encryptedString;
	}
	// Function which returns descryptedString
	public static String stringDecryption(String s)
	{
		// Initializing the string
		String decryptedString = "";
		// Run the for loop for total string
		for (int i = 0; i < s.length(); i++)
		{
			for (int j = 0; j < 26; j++) {

				// compare each characters and decode them
				// using indices
				if (s.charAt(i) == codedChar[j])
				{
					decryptedString += normalChar[j];
					break;
				}
				// Add the special characters directly to
				// the String
				if (s.charAt(i) < 'A' || s.charAt(i) > 'Z')
				{
					decryptedString += s.charAt(i);
					break;
				}
			}
		}
		// return the decryptedString
		return decryptedString;
	}
	public static void main(String args[])
	{
		String str = "hello kasi";
		// print plain text
		System.out.println("Plain text: " + str);
		// Changing whole string to lower case
		// function call to stringEncryption and storing in
		// encryptedString
		String encryptedString = stringEncryption(str.toLowerCase());
		// printing encryptedString
		System.out.println("Encrypted message: "+ encryptedString);
		// function call to stringDecryption and printing
		// the decryptedString
		System.out.println("Decrypted message: "
			+ stringDecryption(encryptedString));
	
	}
}
